Abstract: In order to investigate the amount of alkaloids dissolved in Sanhuang Xiexin Decoction under different acid-base conditions, the contents of total alkaloids in Sanhuang Xiexin Decoction were determined by semi-bionic colorimetric method and bromocresol green acid dye colorimetry. The results showed that the semi-bionic acid dye colorimetric method was feasible for the determination of total alkaloids in Sanhuang Xiexin Decoction, with good linearity, specificity, repeatability and high recovery. The amount of total alkaloids dissolved in Sanhuang Xiexin Decoction was higher than that in the dipping preparation. When the pH was 1.2~6.8,the amount of total alkaloids dissolved first decreased, then increased, and then gradually decreased, presenting a parabolic curve with upward opening. In general, the increase of acidity was conducive to the dissolution of total alkaloids.

Key words: acid dye colorimetry method, semi-bionic method, Sanhuang Xiexin Decoction, total alkaloids